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X-ray imaging demonstration of glass GEM detector with dynamic time-over-threshold-based readout
摘要： Large-scale detection is one of the important roles for gaseous detectors to play in high-energy physics. In many cases, energy resolving multi-channel readout is required. Recent micro-pattern gaseous detectors (MPGDs) have finer pitches or pixels; hence, large-sized detectors have thousands of readout channels. In those cases, it becomes important to reduce the scale and complexity of the readout circuit while keeping its energy resolving capability. The signal processing technique called dynamic time-over-threshold (dynamic ToT, dToT) achieves both the good conversion linearity from analog to digital signal and the compact circuit scale compared with conventional analog-to-digital-converter (ADC)-based readout. In this study, we developed and demonstrated a dToT-based readout circuit for glass gas electron multiplier (glass GEM, G-GEM). The readout circuit showed better linearity than that of normal ToT. We demonstrated the readout circuit by X-ray imaging with the charge-division scheme. The good linearity of the readout circuit enabled imaging over a 100 × 100 mm2 area with small distortion. We expect that the dToT-based readout would be a promising candidate for the future readout of large-scaled MPGDs.
关键词： Digital electronic circuits,Electronic detector readout concepts (gas, liquid),Analogue electronic circuits,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
更新于2025-09-23 15:23:52
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Directionality properties of the nGEM detector of the CNESM diagnostic system for SPIDER
摘要： The ITER project requires additional heating by two neutral beam injectors, each accelerating up to 1 MV a 40 A beam of negative deuterium ions for one hour. Such requirements have never been reached, so it was decided to build in Padova a facility (PRIMA) that hosts two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full-scale injector for the ITER NBI. SPIDER has begun operation in 2018, while MITICA is expected to start after 2020. In both devices the accelerated deuterium beam impinges on an actively cooled beam dump used to stop the deuterons. Detection of fusion neutrons produced between beam–deuterons and dump-embedded deuterons will be used as a means to resolve the horizontal beam intensity profile. A neutron detection system called Close-contact Neutron Emission Surface Mapping (CNESM) is installed right behind the SPIDER beam dump, with the aim to provide the neutron emission map of the beam dump surface. The core of this diagnostic system is an nGEM (neutron-Gas Electron Multiplier) detector which will be able to reconstruct the fast neutron beam profile with an efficiency of about 10?4. A crucial point in order to correctly reconstruct the profile of the deposited D? power is the directionality discrimination capability of the detector. This paper reports on the results of the characterization of the nGEM directionality capabilities, performed at the Frascati Neutron Generator (FNG) using 2.5 MeV neutrons, before installation of the detector inside the SPIDER vacuum vessel.
关键词： Neutral beam injector,Directionality,Neutron imaging,GEM detectors,Deuterium map
更新于2025-09-23 15:22:29
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[IEEE 2018 26th Telecommunications Forum (TELFOR) - Belgrade, Serbia (2018.11.20-2018.11.21)] 2018 26th Telecommunications Forum (TELFOR) - The Next Generation of Passive Optical Networks
摘要： In order to offer end users an efficient multi-service access, it is necessary to implement high quality network access. This paper analyzes the next generation of passive optical networks. It gives a summary view of current researches conducted in the area of passive optical networks, which are directed towards capacity increase using different technologies.
关键词： OFDMA PON,GEM enkapsulacija,WDM PON,DBA algoritam,OCDMA PON,NG-PON
更新于2025-09-19 17:15:36
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Feasibility of gem identification using reflectance spectra coupled with artificial intelligence
摘要： Standard traditional gem identification requires expert supervision, while sophisticated modern methods are time-consuming and expensive. In contrast, reflectance spectroscopy coupled with artificial intelligence is economical and convenient and does not require specialist supervision. This study established an artificial neural network model that consists of standard multilayered, feed-forward, and back-propagation neural networks, and obtained reflectance spectra of a transparent gem (almandine), an opaque gem (turquoise), several almandine imitations (agate, plastic, and glass), and several treated turquoise samples (dyed, impregnated, and Zachery treated) using an Analytical Spectral Devices spectrometer. The acquired spectra were used to train and test the artificial neural network model. The results show that the model can effectively discriminate between genuine and imitation gems of different classes. However, discrimination between natural and treated gems of same class is not as effective as discrimination of gems of different classes. The results suggest that an artificial neural network based on reflectance spectroscopy could serve as a useful tool for preliminary gem identification, and the advanced identification needs further training and investigation.
关键词： reflectance spectrum,artificial neural network,Artificial intelligence,gem identification
更新于2025-09-12 10:27:22
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Monitoring the effect of gas purification of sealed MPGDs for X-ray imaging
摘要： The response of a sealed MicroPatterned Gaseous Detector (MPGD), with an enclosed gas purification system based on getters, was monitored for several weeks. An average of 2 discharges per day was registered during the monitoring period and the charge gain varied a maximum of 15% during the more stable period. The temperature of the getters was varied from 180?C to 250?C and no significant influence was registered in the detector response. A reactivation of the getters also did not affect the charge gain, which means that their gettering rate was at full efficiency before the reactivation. However, careful attention is paid to charge gain reduction for long times of operation which can denote a loss of getters efficiency along time and the need of getter reactivation. On the other hand, turning off the getters lead to a rapid decrease in the charge gain. This allows concluding that a purification system based on getters is really effective in removing gas impurities, being a crucial component of the detection system for a sealed gaseous detector.
关键词： Gaseous detectors,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc)
更新于2025-09-11 14:15:04
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Tomographic capabilities of the new GEM based SXR diagnostic of WEST
摘要： The tokamak WEST (Tungsten Environment in Steady-State Tokamak) will start operating by the end of 2016 as a test bed for the ITER divertor components in long pulse operation. In this context, radiative cooling of heavy impurities like tungsten (W) in the Soft X-ray (SXR) range [0.1 keV; 20 keV] is a critical issue for the plasma core performances. Thus reliable tools are required to monitor the local impurity density and avoid W accumulation. The WEST SXR diagnostic will be equipped with two new GEM (Gas Electron Multiplier) based poloidal cameras allowing to perform 2D tomographic reconstructions in tunable energy bands. In this paper tomographic capabilities of the Minimum Fisher Information (MFI) algorithm developed for Tore Supra and upgraded for WEST are investigated, in particular through a set of emissivity phantoms and the standard WEST scenario including reconstruction errors, in?uence of noise as well as computational time.
关键词： Plasma diagnostics - interferometry, spectroscopy and imaging,X-ray detectors,Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc),Radiation calculations
更新于2025-09-09 09:28:46
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Recent advances in bubble-assisted Liquid Hole-Multipliers in liquid xenon
摘要： We report on recent advances in the operation of bubble-assisted Liquid Hole-Multipliers (LHM). By con?ning a vapor bubble under or adjacent to a perforated electrode immersed in liquid xenon, we could record both radiation-induced ionization electrons and primary scintillation photons in the noble liquid. Four types of LHM electrodes were investigated: a THGEM, standard double-conical GEM, 50 μm-thick single-conical GEM (SC-GEM) and 125 μm-thick SC-GEM — all coated with CsI photocathodes. The 125 μm-thick SC-GEM provided the highest electroluminescence (EL) yields, up to ～ 400 photons per electron over 4π, with an RMS pulse-height resolution reaching 5.5% for events comprising ～ 7000 primary electrons. Applying a high transfer ?eld across the bubble, the EL yield was further increased by a factor of ～ 5. The feasibility of a vertical-mode LHM, with the bubble con?ned between two vertical electrodes, and the operation of a two-stage LHM con?guration were demonstrated for the ?rst time. We combine electrostatic simulations with observed signals to draw conclusions regarding the location of the liquid-gas interface and suggest an explanation for the observed di?erences in EL yield between the investigated electrodes.
关键词： Micropattern gaseous detectors (MSGC, GEM, THGEM, RETHGEM, MHSP, MICROPIC, MICROMEGAS, InGrid, etc),Noble liquid detectors (scintillation, ionization, double-phase),Charge transport, multiplication and electroluminescence in rare gases and liquids
更新于2025-09-09 09:28:46
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The Imaging X-ray Polarimetry Explorer (IXPE)
摘要： Recently selected by NASA as the next SMall EXplorer (SMEX) mission for a launch in 2021, the Imaging X-ray Polarimetry Explorer (IXPE) marks the renaissance of X-ray polarimetry, with the prospect of measuring linear polarization from tens of astronomical X-ray sources. IXPE will expand the X-ray view of the Universe by providing new and unique insight into our understanding of some of the most violent celestial objects, such as stellar and supermassive black holes and neutron stars. In this contribution we shall discuss the scientific prospects of the mission, as well as the status of the program, with particular emphasis on the development of the focal plane detectors sensitive to polarization.
关键词： Imaging,Micro-pattern gas detectors,GEM,X-ray,Polarimetry
更新于2025-09-09 09:28:46
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High resolution TPC based on optically readout GEM
摘要： Large granularity and high sensitivity commercial CMOS readout systems open the possibility of developing particle detectors with very interesting performance for different applications, from the search of rare and exotic events, such as dark matter directional candidates, to high quality neutron/ion/hadron beam monitor, mainly for medical applications. The gas scintillation mechanism was exploited for starting an R&D on large TPC-based detector, equipped with a Triple GEM amplification stage optically readout. By this approach, a 7 litre sensitive volume detector was built and tested. Space resolutions of 35 μm on the GEM plane (X,Y) and 100 μm on Z and energy measurements with a precision of about 25% were obtained. Analysis of the track shapes provides precious information allowing very good particle discrimination.
关键词： Micro-pattern Gas Detectors,GEM,Tracking detectors
更新于2025-09-09 09:28:46